Fructose, in the form of corn syrup of high fructose content, has been increasingly used as a sweetener in the food industry, in view of the fact that it is 1.5 to 1.7 times sweeter than sucrose. Lower calorie products having the same sweetness can be produced when fructose is used as the sweetener as opposed to sucrose, glucose or maltose.
High fructose content corn syrups are conventionally derived from corn starch by a series of steps. In the first step, starch liquifaction and saccharification are effected using enzymatic and/or acid hydrolysis of the starch to yield a glucose containing syrup. Part of the glucose in the syrup then is isomerized to fructose, thereby forming a syrup containing reducing sugars in the weight proportions of about 42% fructose, 50% glucose and 8% higher saccharides. The latter syrup then is enriched and refined by fractionation to yield two products, namely a first syrup containing reducing sugars in the weight proportion of 90% fructose and 10% glucose and a second syrup containing reducing sugars in the weight proportion of 85% glucose and 15% higher saccharides.
There are three types of high fructose corn syrups available, namely one in which the reducing sugars comprise about 42 wt% fructose, which is produced by the hydrolysis and isomerization steps described above, one in which the reducing sugars comprise about 90 wt% fructose which is produced by fractionation of the 42 wt% fructose syrup as described above, and one in which the reducing sugars comprise about 55 wt% fructose which is produced by blending the 42 wt% fructose syrup and the 90 wt% fructose syrup in the required proportions.
The fractionation procedure which is used to form the 90 wt% syrup requires somewhat sophisticated technology and, as a result, the 90 wt% fructose syrup is an expensive material. Production of this material nevertheless is required to enable the 55 wt% fructose syrup, which is the fructose syrup most in demand by the food industry, to be produced by blending with the 42 wt% fructose syrup.